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Alternative methods of selection for litter size in mice.

Abstract

Alternative methods of selection for litter size are discussed for application in a population of mice. Selection based on an index of ovulation rate and total number born/ovulation rate and on litter size in unilaterally ovariectomized females are being carried out and compared to ordinary litter size selection and a control. Selection on the index is expected to place a more optimum weighting on the components of litter size than does selection on the natural index. Selection in unilaterally ovariectomized females is designed to challenge uterine potential and possibly increase the expression of genetic variation for selection. Discussion of reasons for the alternative methods, procedures with which the selection methods are carried out and early results from four generations of selection are presented.